[OT] Virtualization (WAS: UNIX V7)

Ethan Dicks ethan.dicks at gmail.com
Thu Jun 11 15:14:34 CDT 2009

On Thu, Jun 11, 2009 at 3:51 PM, Kirn Gill<segin2005 at gmail.com> wrote:
> If you were to attempt to run a full virtualization engine on, e.g., a
> 486DX2, the guest would probably run so slow that you could debug each
> executed instruction in real-time.

Years and years ago, when simh first broke onto the scene, my "fast"
machine was a SPARC1 (20Mhz/12 MIPS) w/64MB of memory.  One of the
first things I loaded up, since I had real tapes on hand, was 2.9BSD.
It was quite a bit slower than a real PDP-11, but I didn't have any
real PDP-11 disks over 10MB, so the virtual environment was "better"
because I could allocate 40MB of my 1.8GB disk to hold the guest OS.

Fortunately, when I was debugging a problem with the RP module, I had
moved up to a SPARC5 which ran a virtual PDP-11 faster than the real
thing.  Given how many times I rebooted the virtual PDP-11, I was very
happy to be doing this on a faster platform.

Speed isn't everything, but it sure is nice when you can get it.


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